what happens if the 12v accessory battery dies?

will the main battery keep it alive to prevent it from dying?

i ask because i am in the process of installing a dash cam. if i hook this up to the 12v accessory battery, will the main battery just keep the accessory battery charged up when the engine is off? or will i be in a situation where my 12v accessory battery goes dead and the car doesn't start even though i have plenty of main battery left?

i also have a power magic pro that i can use to stop the dash cam power if the 12v accessory battery goes below 12v but if i don't need to use it, i won't.

RVD.

Odds are very good you will wind up with a dead 12 volt battery. With the car off, the main battery is only topped up every 5 days.

RVD said:

if i hook this up to the 12v accessory battery, will the main battery just keep the accessory battery charged up when the engine is off?

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Tom is right. I think newer models top off every few days so not quite as long but still too long. you might as well leave the radio on in a regular car. same results. now it wouldnt be so bad if the LEAF actually did top off the battery but it doesnt. just gives it a small boost. not enough to recharge it to full... just a small boost

Do you plan on recording 24/7? Or, are you thinking of using the motion-detect feature to record if someone gets near the car? I just installed a dash cam also, as per another post on this forum, but I cut into an accessory wire that powers the camera off when I shut the car off, so no battery drain, no problem. Do you have the SL model with the solar panel that charges the 12 volt battery?

sorry for the late response.

i do have the SL with solar power but i also live in Seattle where sometimes we don't get a lot of sun.

i plan to record motion only when stopped.

right now i have it hooked up to a fuse that turns off when i turn off the car. i would like to switch it though to a fuse that is always on. of course i could always just try it and see what happens but thought i'd ask here first.

i drive the car every day.

12v batt dies car won't start

If you really want to go with this configuration, replace the OEM battery with the biggest AGM deep cycle battery that will fit, add hardwiring for a battery maintainer that can deliver 5-10 amps, and make sure you keep it charged via the maintainer, because the car won't do it for you.

LeftieBiker said:

If you really want to go with this configuration, replace the OEM battery with the biggest AGM deep cycle battery that will fit, add hardwiring for a battery maintainer that can deliver 5-10 amps, and make sure you keep it charged via the maintainer, because the car won't do it for you.

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That is a very interesting idea.
You're still going along the lines of with the car off, that the battery won't be maintained, right?

I've been reading the threads about battery longevity/duration of available power and am now wondering about your idea of replacing the OEM battery.
What is the OEM battery? A deep cycle? How many AmpHour is it?

So, what if you replaced the OEM battery like you suggested with the largest deep cycle battery you can get;
Would this battery fully charge when you were charging the vehicle via the charging port? Or were you saying that there will be a limited amount of charge sent to the accessory battery no matter what you do?

This idea you have, if it worked out, would seem to me to give us a way to be able to use a lot more auxiliary power while we are doing activities at the park, etc.
I mean if there is a big difference between the amphours of the OEM battery and it's larger replacement deep cycle battery. I would imagine that I could run my laptop while the car is off for quite an extended amount of time with a larger deep cycle battery. And I would consider bringing a flexible solar panel with me to the park to help recover some of that usage.
Sounds saweet to me!

Many dash cams don't use much power, especially in parked mode. I would probably stick with the 'power magic pro' module, which cuts off power to the cam if battery voltage drops too much (I have one on my bench, still need to install the power magic pro myself).

What is the OEM battery? A deep cycle? How many AmpHour is it?

So, what if you replaced the OEM battery like you suggested with the largest deep cycle battery you can get;
Would this battery fully charge when you were charging the vehicle via the charging port? Or were you saying that there will be a limited amount of charge sent to the accessory battery no matter what you do?

This idea you have, if it worked out, would seem to me to give us a way to be able to use a lot more auxiliary power while we are doing activities at the park, etc.

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The OEM battery is some kind of flooded cell - I haven't seen exactly what the designation is, or what the AH rating is, but it isn't big enough or resilient enough for the car's poor charging behaviors. The Leaf charges the 12 volt battery only a bit while plugged in, so many of us use battery maintainers, preferably accessible to plug in through the charging port. A bigger, AGM or gel type battery would let you use accessory power more safely, but only if you keep it charged with an external charger, as I suggested. You shouldn't use Accessory mode at all, though, if you can help it. Use On or Ready mode when the car is parked, even if you put in a larger battery.

DaveinOlyWA said:

Tom is right. I think newer models top off every few days so not quite as long but still too long. you might as well leave the radio on in a regular car. same results. now it wouldnt be so bad if the LEAF actually did top off the battery but it doesnt. just gives it a small boost. not enough to recharge it to full... just a small boost

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All models do this.

Can one charge the 12v battery while still connected in the car, with car in OFF position, using home car battery charger (110v). If yes do I connect the alligator clips directly to the battery like I do with my ICE vehicles. Thanks in advAnce

Are there any benefit to charge the 12v. Monthly or qtrly?

goixiz said:

Can one charge the 12v battery while still connected in the car, with car in OFF position, using home car battery charger (110v). If yes do I connect the alligator clips directly to the battery like I do with my ICE vehicles. Thanks in advAnce

Are thereby benefit to charge the 12v. Monthly or qtrly?

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Not exactly sure what you are asking but you can not charge the LEAF using the accessory "cigarette lighter" port as this is turned off when the car is off. Connecting your charger to the positive battery terminal and then the negative to somewhere besides the negative terminal.

There probably isn't much benefit to charging it monthly/quarterly. Not frequently enough for a desulfator to work and the full battery will go back to its normal state after you let the car take over.

Definitely would be a good idea whenever leaving the car sitting for a few days just to guarantee that it doesn't drain.

I went on a trip for two weeks, leaving the car in the garage with the regular charger plugged in.
After about a week, the car started sending "charging complete" once an hour. After being annoyed by that for two days, I turned off updates of charging status to my phone.
When I came home, the car was entirely dead. The 12V battery had drained.

Reading in this forum, I find this:

The primary problem is when the vehicle is left plugged-in for multiple days, which throws a double-whammy at the 12V battery
1 - The vehicle draws much more "dark current" than when unplugged
2 - Top-off charging by the DC-DC converter is inhibited.

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That's certainly not described in the owner's manual, and it's a really, really, dumb way to build the car. I had assumed that, if there is electricity hooked up, it would maintain a float voltage on the 12V battery of something like 13.8V. The circuitry to do this, safely, costs less than a dollar in automotive qualit and low quantities (and could probably be effectively "free" to Nissan if properly designed-in.)

When the car didn't start, I charged the battery at 10A for a few minutes, and then started the car, because I needed to actually go somewhere (and I was still a few minutes late.)
However, some things in the car do not behave like they did before:
- the estimate for turning off A/C now says "turn off A/C for +20 miles" when before it would say +3 miles
- the driver side window no longer automatically closes when I pull the switch up
- the "average mileage efficiency" now shows 2.7 mi/kWh when before it showed 3.4 mi/kWh

First, is there some kind of user reset I can do to bring these things back to normal?

And second, regarding the plugged-in charging cable draining the battery: What the hell? Really? Like,... really?

jwatte said:

- the estimate for turning off A/C now says "turn off A/C for +20 miles" when before it would say +3 miles
- the driver side window no longer automatically closes when I pull the switch up
- the "average mileage efficiency" now shows 2.7 mi/kWh when before it showed 3.4 mi/kWh

First, is there some kind of user reset I can do to bring these things back to normal?

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#1 and #3 will correct themselves as the car "re-learns" things.
#2 can be fixed by rolling down the window, then holding the switch all the way up until the window is rolled up and keep holding for about an extra 5 seconds.

is it possible to disable that auto window roll up feature?

johnrhansen said:

is it possible to disable that auto window roll up feature?

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I couldn't find anything in the Service Manual indicating so.

Thanks, DarkStar!

I'm still quite frustrated (as a consumer) and surprised (as an engineer) that the battery will die while the car is plugged in -- and so quickly...

jwatte said:

Thanks, DarkStar!

I'm still quite frustrated (as a consumer) and surprised (as an engineer) that the battery will die while the car is plugged in -- and so quickly...

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Clearly Nissan needs to work on the 12v charging algorithm but part of the issue is that the "high voltage"/line voltage from the EVSE is only on when the car is actively charging and the DC to DC inverter is only on when the main traction battery contractors are closed. So with that setup they can't trickle charge 24/7 like you propose.

johnrhansen said:

is it possible to disable that auto window roll up feature?

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Well, yeah! Disconnect your 12V battery for awhile.